org.josql.expressions

类 ExpressionList

java.lang.Object

org.josql.expressions.Expression

org.josql.expressions.ValueExpression

org.josql.expressions.ExpressionList

public class ExpressionList
extends ValueExpression

构造器概要

构造器

构造器和说明
ExpressionList()

方法概要

限定符和类型	方法和说明
void	addExpression(Expression expr) Add an expression to the list.
Object	evaluate(Object o, Query q) Evaluates the value of this expression list.
Class	getExpectedReturnType(Query q) Get the expected return type, which is List.
List	getExpressions() Returns the expressions, a list of Expression objects.
Object	getValue(Object o, Query q) Gets the value of the expressions, this will return a list of the values for each of the expressions in the list.
boolean	hasFixedResult(Query q) Returns true if this expression list is empty (no expressions) or if ALL of the expressions have a fixed result.
void	init(Query q) Initialises this expression list, each expression in the list is inited.
boolean	isTrue(Object o, Query q) Returns true if one of the expression values is non-null.
void	setExpressions(List exprs) Set the expressions.
String	toString() Returns a string version of this expression list.

从类继承的方法 org.josql.expressions.Expression

isBracketed, setBracketed

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

构造器详细资料

ExpressionList

public ExpressionList()

方法详细资料

getExpectedReturnType

public Class getExpectedReturnType(Query q)

Get the expected return type, which is List.

指定者:

getExpectedReturnType 在类中 Expression

参数:

q - The Query object.

返回:

List.

init

public void init(Query q)
          throws QueryParseException

Initialises this expression list, each expression in the list is inited.

指定者:

init 在类中 Expression

参数:

q - The Query object.

抛出:

QueryParseException - If one of the expressions cannot be inited.

getExpressions

public List getExpressions()

Returns the expressions, a list of Expression objects.

返回:

The expressions.

addExpression

public void addExpression(Expression expr)

Add an expression to the list.

参数:

expr - The expression.

setExpressions

public void setExpressions(List exprs)

Set the expressions.

参数:

exprs - The expressions.

getValue

public Object getValue(Object o,
                       Query q)
                throws QueryExecutionException

Gets the value of the expressions, this will return a list of the values for each of the expressions in the list. In essence Expression.getValue(Object,Query) is called on each of the expressions.

覆盖:

getValue 在类中 ValueExpression

参数:

o - The current object.

q - The Query object.

返回:

A list of the values, if there are no expressions in the list then an empty list is returned.

抛出:

QueryExecutionException - If something goes wrong the acquisition of the values.

isTrue

public boolean isTrue(Object o,
                      Query q)
               throws QueryExecutionException

Returns true if one of the expression values is non-null. Note: for efficiency this method calls Expression.getValue(Object,Query) on each expression directly and returns true for the first non-null value found, as such if any of your expressions triggers side-effects then this method should not be used.

指定者:

isTrue 在类中 Expression

参数:

o - The current object.

q - The Query object.

返回:

true if one of the expression values is non-null.

抛出:

QueryExecutionException - If a problem occurs during evaluation.

evaluate

public Object evaluate(Object o,
                       Query q)
                throws QueryExecutionException

Evaluates the value of this expression list. This is just a thin-wrapper around: getValue(Object,Query).

指定者:

evaluate 在类中 ValueExpression

参数:

o - The current object.

q - The Query object.

返回:

The value of this expression list.

抛出:

QueryExecutionException - If there is a problem getting the values.

toString

public String toString()

Returns a string version of this expression list. Returns in the form: "[" Expression [ , Expression ]* "]".

指定者:

toString 在类中 Expression

返回:

A string version of the expression list.

hasFixedResult

public boolean hasFixedResult(Query q)

Returns true if this expression list is empty (no expressions) or if ALL of the expressions have a fixed result.

指定者:

hasFixedResult 在类中 Expression

参数:

q - The Query object.

返回:

See description.